检测TCP端口号是否被占用

 string tcpPort = this.txtTCP.Text.Trim();
            try
            {
                if (tcpPort == "" || tcpPort == null)
                {
                    this.lblMessage.Text = "";
                    MessageBox.Show("请输入TCP端口号！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
                }
                else
                {
                    Process process = new Process();
                    process.StartInfo = new ProcessStartInfo("netstat", "/ano");
                    process.StartInfo.CreateNoWindow = true;
                    process.StartInfo.UseShellExecute = false;
                    process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
                    process.StartInfo.RedirectStandardOutput = true;
                    process.Start();
                    StreamReader reader = process.StandardOutput;
                    while (!reader.EndOfStream)
                    {
                        string msg = reader.ReadLine().ToUpper();
                        if (msg.IndexOf("TCP") > 0 && msg.IndexOf(":" + tcpPort) > 0)
                        {
                            string info=msg.Trim();
                            this.lblMessage.Text = "TCP进程的PID为：" + info.Substring(info.Length - 5, 5);
                            MessageBox.Show("TCP：" + tcpPort + "端口被占用！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
                            break;
                        }
                        else
                        {
                            this.lblMessage.Text = "";
                        }
                    }
                    reader.Close();
                    process.Close();
                }
            }
            catch (Exception ex)
            {
                SaveError(FilePath + "TCPError.log", "检测TCP端口："+tcpPort+"失败！"+ex.Message);
                MessageBox.Show("检测TCP端口："+tcpPort+"失败！" + ex.Message, "提示", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
            }